Floor mat with electrical switch

ABSTRACT

A floor mat which produces an electrical signal upon a force being applied, as by being stepped upon, by the force flexing a portion of a pair of spaced apart metal plates into engagement to complete a circuit and in which the plates are embedded within and adhered to a thick cured polyurethane covering material.

Newman 1 FLOUR MAT Wll'lllll ELECCAL SWTTCIH [75] Inventor: Barry 6.Newman, Monsey, NY. [73] Assignee: Marc Manufacturing llnc., Stratford,

[11] 3 21 .5 June 2,1974

3,323,197 6/1967 Millard 200/86 R Primary Examiner-David Smith, Jr.Attorney, Agent, or Firm-Ernest M. .lunkins 5 7 ABSTRACT A floor matwhich produces an electrical signal upon a force being applied, as bybeing stepped upon, by the force flexing a portion of a pair of spacedapart metal plates into engagement to complete a circuit and in whichthe plates are embedded within and adhered to a thick cured polyurethanecovering material.

3 Claims, 5 Drawing Figures ll FLOOR MAT WITH ELECTRICAL SWTTCH Theelectrical switch floor mat to which the present invention is directedhas special utility when used to control the automatic opening of a doorfor a pedestrian or a vehicle. Normally such a mat is positioned on thefloor adjacent the door and the force applied by a weight thereon causesclosing of the switch within the mat which completes a circuit thatcontrols an automatic door opening mechanism. With the removal of theweight, the circuit becomes open and the door closes.

The electrical components include a pair of metal plates, substantiallythe same size as the mat, that are normally placed slightly apart byresilient inserts therebetween. When a weight is applied, the insertsare compressed and the upper plates flexes somewhat so that it touchesthe lower plate in the area where the weight is applied to complete thecircuit between the two plates. Upon removal of the weight, the platesagain revert to being spaced apart and non-touching.

To provide protection for the plates, a skid resistant surface,acceptable appearance, etc., the plates have heretofore been enclosed ina covering material, either by laminating them between two layers ofresilient material or by molding the material about the plates with thematerial heretofore suggested being rubber and/or polyvinyl chlorides.Such mats however have not been found sufficiently satisfactory becausethey malfunctioned easily and were not durable. One reason for thisappears to be that the covering material merely acted as an envelope forthe plates without any significant cooperation between the coveringmaterial and the plates.

It is accordingly an object of the present invention to provide a floormat which has a weight responsive electrical switch which is extremelydurable, but still remains relatively sensitive to a light actuatingweight.

Another object of the present invention is to provide a floor mat of theabove type in which the covering material is made to adhere to andremain bonded to the plates over the useful life of the mat.

A further object of the present invention is toprovide a weightresponsive floor mat which, while achieving the above objects, iscapable of being reliably manufactured by having the covering materialmolded about the plates.

Another object of the present invention is to provide a floor mat of theabove type in which a visible design may be easily incorporated into themat.

In carrying out the present invention, the floor mat includes a pair ofsheet metal plates that are relatively thin so as to be somewhatflexible and which are just slightly smaller in shape than the mat. Thininserts of resilient insulating material such as sponge rubber are gluedat spaced locations between the plates intermediate the edges whilesimilar material is located about the edges. The plates are thenpositioned in a mold and a curable polyurethane resin composition isflowed about the plates to completely cover them and to have the desiredshape of the final that. The polyurethane composition is then cured toproduce the finished mat.

Of particular importance in the present invention is the preparation ofthe surface of the plates and the selection of polyurethane coveringmaterial, to secure a bond therebetween. The bond aids the mat in beingsubstantially more resistant to abuse that had heretofore causedmalfunctioning and hence more durable.

While the polyurethane covering may have the color which the mat isdesired to have, it has also been found that an essentially clearpolyurethane material may also be used. With clear material, a designmay be painted onto the top surface of the plate with an enamel or thelike and be visible through the covering. Such an enamel moreover isselected to maintain the adhesion between the covering material and theplates.

Other features and advantages will hereinafter appear.

In the drawing;

FIG. 1 is a perspective view of a floor mat, made in accordance with thepresent invention, somewhat reduced in size.

FIG. 2 is a cross-section taken on line 2-2 of FIG. 1, enlarged to fullsize.

FIG. 3 is a diagrammatic representation showing .electrical connectionsto the metal plates.

FIG. 4 is a view similar to FIG. 1 but having a visible design.

FIG. 5 is a cross-section, taken on line 55 of FIG. 4-, enlarged to fullsize.

Referring to the drawing, the mat of the present in vention is generallyindicated by the reference numeral 10 and consists of a polyurethanecovering material 11 into which is embedded a pair of identical steelplates 12 and 13. The plates are preferably formed of sheet steel, of 22or 26 gauge thickness, and are separated by a plurality of small rubbercompressible inserts 14 glued to the plates at selected intervalsthroughout the plates. In addition, a similar strip of rubber, such assponge rubber, having a rectangular cross-section and indicated by thereference numeral 15 is glued about the edges of the plates to enclosethe periphery thereof.

As shown in FIG. 3, each of the plates may have a similar off centeredcut-out 16, so that a wire 17 may be soldered or otherwise secured tothe lower plate 13 and a similar wire 18 secured to the upper plate. Ifa voltage is applied across the two wires 17 and 18 and a weight isapplied to the plate, the rubber inserts 14- will be compressed and theplate will flex slightly so that the upper plate touches the lower plateto complete the circuit between the two wires 17 and 18. When the weightis removed, the plates separate to open the circuit. If they do not, andthey continue to touch without a weight on the mat, then the switch ismalfunctioning.

The particular spacing of the inserts 14, their resilience andthickness, basically set the weight which operates the switch. In oneexample, where the mat is about 3 X 6 feet, the insert M (and strip 15)are 1/16 of an inch thick and positioned on about 10 inch squares sothat the nonnal space between the plates is about I/ l 6 of an inchwhich enables a person having a weight of more than 30 lbs. or so tooperate the switch.

The plates 12 and 13 are encased by the covering material 11 with thelatter having a thickness of perhaps /2 inches. The upper surface 19 ofthe covering may be grooved. in order to provide a slip resistantsurface while the edges may be beveled as at 20 to facilitate securementof the mat to the floor by the use of elongate metal clips. It will beunderstood that in addition to th size of the mat being variable, thesurface 119 may also 3 be of a different grooved construction as may theedges 20.

The covering 11 is colored to make it opaque and render the platesindiscernable with one common color being black. With an opaquecovering, it was quite difficult to form in the covering a design orother visible signs of a different color or colors on the surface.However the mat shown in FIGS. 4 and 5 enables a visible design to beeasily incorporated into the mat. The design is formed as a painted film21 on the upper surface of the upper plate 12 with the films thicknessbeing exaggerated for clarity in the drawing. The covering material 11is clear or slightly colored, as for example, only a light amber andthus when the plates are embedded in the covering material the film 21clearly shows to be visible. Thus, by simply painting the film 21 tohave the desired design and using an essentially colorless coveringmaterial lll, a visible design may be easily incorporated into the mat.Moreover, in order to disguise the colorless edges of the mat, where theplates are not present, a film of paint, as for example 22, may beapplied to the bottom surface of the mat and have a color whichcorresponds to the background color of the film 21 to thus provide thesame color along the edges of the mat as in the design to therebydisguise the edges of the plates.

in both embodiments of the invention, the covering material 11 is apolyurethane material that is preferably formed into the desired shapedmat by being poured into a moled having a cavity that corresponds to thede sired shape of the mat with the plates 12 and 13 being positionedwithin the mold. The liquid curable polyurethane resin composition flowsthroughout the cavity to assume its shape, is then substantially curedor hardened and the finished cured mat is then removed from the mold.

One form of polyurethane material that has been found especiallyadvantageous in the present invention is a type of polyurethane materialthat is used as moldforming material for casting plastic parts in thefurniture industry. Such polyurethane material is used to form flexiblemolds, for molding rigid foam furniture parts. One type of material thathas been found to be advantageously employed has the properties, afterbeing cured at 80 C. for 16 hours; of being normally light amber incolor, having a tensile strength of 2200 psi., an elongation percentageof 900 percent, a tear strength of 250 Graves, pli; a hardness of 75plus or minus 5 Shore A, and a shrinkage of .5 to .75 percent. One typeof such material is sold under the tradename CONATHANE TU-SO by Conap,Inc., Allegany, NY. 14706.

In both embodiments, the adherence of the polyurethane covering to thesurfaces of the plates basically approximates the cohesion of the curedpolyurethane elastomer so that an attempt to strip the covering from theplates is as apt to result in a tearing of the polyurethane covering asit is to become free from the plates. Moreover, as the polyurethane isapplied throughout the surfaces of the plate and as the plate surfaceshave throughout been treated so as to be free of material which wouldprevent adhesion, the same adhesion exists throughout the entiresurfaces of the plates.

The use of a polyurethane that assures adhesion to the plates 12 and 13provides a mat that is substantially more capable of resisting abuse,before malfunctioning, than in other kinds of floor mats. One type ofnormal abuse is the cutting of a slit in the top surface of the coveringto the top surface of the plate 12. However, with the adhesion presentas herein disclosed, the only portion of the plate 12 that issusceptible to moisture occurring in the slit is only at the slit as theadhesion prevents the spreading of the moisture between the covering andthe plates to enter between the two plates and short circuit them.Another type of normal abuse is caused by extremes in temperatures whichtends, without adhesion, to form a slight bubble between the plate andthe covering material and as the mat is continually stepped on thebubble in effect spreads and not only becomes a possible hazard but alsocould be forced towards the edges of the mat and serve to form anopening in the mat again through which moisture could enter to effecteither a short circuiting or a rusting of the plate.

Still another type of abuse which could cause malfunctioning of the matis that which may result from dents when for example a small stone has aheavy weight placed thereon so that the stone forms a small inwardlyextending dent that remains even after the plates resume their normalspaced apart position. It has been found that the adhesion of thepolyurethane covering to the plates makes the mat less subject to thistype of malfunctioning by reason not only of the characteristics of thepolyurethane covering but also by the adhesion thereof to the platesincreasing the resistance of the material 11 to spreading when a heavyweight is applied to a small area.

While one specific composition of polyurethane material has been setforth, it will be understood that other and different compositions maybe used provided each has the necessary exterior physical propertiessuch as tear resistance, toughness, etc.; is capable of being moldedabout the plates so as to form the mat without any seams and is capableof adhering to the plates. Similarly, the type of paint for forming thedesign film 21 also has to be selected so as to provide the abovedescribed adhesion with the polyurethane covering material. Commerciallyavailable spray-can enamels have been found to be successful. When theplates are used directly as in FIGS. 1 and 2, they are preferablychemically cleaned to assure adhesion.

It will accordingly be appreciated that there has been disclosed a floormat having an electrical switch which is actuated'by a weight on themat. This weight which may be on the order of 30 lbs. or so in the areaof the size of a human foot, causes a flexing, at least in the areawhere the pressure is applied, to occur of a steel plate which is formedto be one part of a circuit and there is sufficient flexing to cause theplate to engage a bottom plate which is connected to the other side ofan electrical circuit to thereby close the circuit. Such a signal may beused to operate an automatic door opener. It has been found that a floormat may be rendered substantially more durable and resist abuses whichcould cause malfunctioning if the steel plates are embedded in a curedpolyurethane elastomer which, while also having its own characteristics,is caused to adhere throughout to the surfaces of the plates. Thisadherence has been found to increase the abuse which the mat may resistbefore it malfunctions.

Variations and modifications may be made within the scope, of the claimsand portions of the improvements may be used without others.

I claim:

l. A floor mat for providing an electrical signal upon a weight beingapplied thereto comprising a pair of somewhat resilient metal plates,means resiliently maintaining the plates contiguous and slightly spacedapart, an electrical connector to each plate and a cured polyurethaneone piece covering material completely enclosing said plates to form amat slightly larger than the plates by said covering material beingmolded to the desired shape with the plates being positioned therein,said covering material being cohesive and adhering to the platesthroughout their contacting surfaces and in which the adhesion of thecovering material through the surfaces of the plates essentiallyapproximates the cohesion of the covering material.

2. A floor mat for providing an electrical signal upon a weight beingapplied thereto comprising a pair of somewhat resilient metal plates,means resilientlymaintaining the plates contiguous and slightly apart,an electrical connector to each plate and a cured polyurethane coveringmaterial completely enclosing said plates to form a mat slightly largerthan the plates, a film adhered to the top surface of the top plateforming a design and in which a polyurethane covering is essentiallycolorless and adheres to the film whereby said design is visable throughthe film.

3. The invention as defined in claim 2 in which at least the bottomsurface of the periphery of the covering material extending beyond theplates is covered by

1. A floor mat for providing an electrical signal upon a weight beingapplied thereto comprising a pair of somewhat resilient metal plates,means resiliently maintaining the plates contiguous and slightly spacedapart, an electrical connector to each plate and a cured polyurethaneone piece covering material completely enclosing said plates to form amat slightly larger than the plates by said covering material beingmolded to the desired shape with the plates being positioned therein,said covering material being cohesive and adhering to the platesthroughout their contacting surfaces and in which the adhesion of thecovering material through the surfaces of the plates essentiallyapproximates the cohesion of the covering material.
 2. A floor mat forproviding an electrical signal upon a weight being applied theretocomprising a pair of somewhat resilient metal plates, means resilientlymaintaining the plates contiguous and slightly apart, an electricalconnector to each plate and a cured polyurethane covering materialcompletely enclosing said plates to form a mat slightly larger than theplates, a film adhered to the top surface of the top plate forming adesign and in which a polyurethane covering is essentially colorless andadheres to the film whereby said design is visable through the film. 3.The invention as defined in claim 2 in which at least the bottom surfaceof the periphery of the covering material extending beyond the plates iscovered by an opaque film.